CAPITALIZED EXPLORATORY WELL COSTS

The following summarizes the changes in capitalized exploratory well costs for each of the last three years ended December 31, 2017, 2016, and 2015. Additions pending the determination of proved reserves excludes amounts capitalized and subsequently charged to expense within the same year.



	2017			2016			2015
	(In millions)
Balance at January 1	$	264		$	245		$	849
Additions pending determination of proved reserves	477			249			382
Divestitures and other	(3		)	—			(557		)
Reclassifications to proved properties	(373		)	(211		)	(369		)
Charged to exploration expense	(15		)	(19		)	(60		)
Balance at December 31⁽¹⁾	$	350		$	264		$	245


(1)	Includes $2 million of assets related to the Canada divestiture at December 31, 2015.

The following provides an aging of capitalized exploratory well costs and the number of projects for which exploratory well costs have been capitalized for a period greater than one year since the completion of drilling:



	2017		2016		2015
	(In millions)
Exploratory well costs capitalized for a period of one year or less	$	160	$	119	$	184
Exploratory well costs capitalized for a period greater than one year	190		145		61
Balance at December 31	$	350	$	264	$	245

Number of projects with exploratory well costs capitalized for a period greater than one year	4		3		2

The following summarizes a further aging by geographic area of those exploratory well costs that have been capitalized for a period greater than one year since the completion of drilling at December 31, 2017:



							2014 and
	Total		2016		2015		Prior

North Sea	$	160	$	47	$	53	$	60
Other International	30		—		28		2
	$	190	$	47	$	81	$	62

Projects with suspended exploratory well costs capitalized for a period greater than one year since the completion of drilling are those identified by management as exhibiting sufficient quantities of hydrocarbons to justify potential development. Management is actively pursuing efforts to assess whether reserves can be attributed to these projects.

Suspended exploratory well costs capitalized at December 31, 2017 for a period greater than one year since the completion of drilling primarily relate to the Seagull, Corona, and Storr discoveries in the North Sea. The Seagull joint venture partnership has selected the host facility and expects to complete the field development plan in late 2018 and achieve the final investment decision by 2019. The suspended exploratory well costs related to the Corona discovery are pending development plan approval. In December 2016, the Company submitted the full field development plan to the Oil and Gas Authority in the U.K. which has been conditionally approved and awaits the U.K. Business, Energy and Industrial Strategy environmental approvals expected by the second quarter of 2018. The final investment decision will be approved in 2018. Storr was a more recent discovery in the North Sea and development plans are actively being evaluated to bring forth a Storr field development plan during 2018 with final investment decision expected to take place in 2019.

The remaining capitalized well costs in excess of one year relate to exploratory drilling in Suriname. Well costs have been suspended pending ongoing activities, including analysis of well results and geologic and geophysical studies of nearby blocks. Remaining activities required to classify the associated reserves as proved include additional exploratory and appraisal drilling, geologic and geophysical studies, reservoir modeling and simulation, economic modeling, pre-development studies, approval of development plans, and project sanctioning.